This invention is related generally to inflatable vehicle protective devices and, more particularly, to an inflatable knee bolster.
Inflatable knee bolsters have been developed to enhance vehicle occupant protection in the event of sudden vehicle deceleration. Such devices increase the duration of deceleration of occupants"" femurs and control upper torso kinematics during a frontal impact event. The bolster impact surface is moved from a stored position to an extended position to intercept an occupant""s knees early in the impact event. This allows the knees more time to decelerate to the vehicle""s final velocity. The initial positioning of the bolster impact surface in a retracted, stored position allows more styling flexibility and enhances occupant ingress and egress.
Typical inflatable knee bolster installations comprise an inflatable air bag sandwiched between an impact surface and a reaction surface. When the inflator is triggered, the air bag expands to move the impact surface a predetermined distance to active position. This position may be determined by tethers between the reaction and impact surfaces. These installations comprise numerous parts, bits and pieces and require careful installation.
It would be desirable to provide a simpler inflatable knee inflatable bolster which would be less costly to manufacture and assemble into the vehicle. To this end it is believed to be advantageous to utilize bolster configurations which utilize a relatively small number of components which may be easily assembled and which exhibit effective deployment in an operational situation.
It is an object of this invention to provide a simpler inflatable knee bolster which would be less costly to manufacture and assemble into the vehicle.
This invention provides advantages and alternatives over typical prior knee bolster installations by providing an inflatable knee bolster which may be deployed from a stored state to an operational state by expansion of the bolster body itself. Such configuration reduces and more preferably eliminates any reliance on the use of an air bag within the bolster structure thereby reducing the complexity of assembly and installation and effecting a reduction in the number of active components within the operating device.
In one aspect this invention features an inflatable bolster for a vehicle occupant having an outer wall that is projected outwardly from a stored position to an extended position by inflation of an expansible chamber by an inflator. The expansible chamber includes a unitary hollow body having an outer wall and an inner wall interconnected by U-shaped normally folded accordion pleats. An attachment tab extends from the top of the chamber for attachment to vehicle structure, and another attachment tab extends from the bottom of the chamber for attachment to vehicle structure. Alternatively, the bottom of the outer surface could be attached directly to vehicle structure.
In another aspect of this invention, the bolster is an inflatable knee bolster having an outer wall that is projected outwardly to an extended position adjacent the occupant""s knees by inflation of an expansible chamber by an inflator. The outer and inner walls are interconnected at their bottoms by a bottom wall and at their tops and sides by the accordion pleats which are U-shaped and extend from the bottom side corners up the sides and across the top of the body. The top tab is a frangible tab which is broken by expansion of the expansible chamber, allowing the outer wall to pilot about the bottom wall and extend. Preferably, tethers on the frangible tab limit movement of the outer wall. Also, vent holes are preferably included to provide subsequent controlled deflation of the expansible body. The hollow body is preferably a blow molding of polypropylene.
According to another aspect of the present invention, an inflatable knee bolster of multipiece construction is provided. The bolster is formed of separate portions forming the face and an expansible body which are joined about their peripheries. Formed within the body portion are a plurality of at least partially collapsible profile elements extending in raised and lowered profile within the cavity between the face and the expansible body. At least a portion of the profile elements undergo collapsible deformation upon pressurization of the cavity by an inflator thereby expanding the volume of the cavity and forcing the face outwardly from a stored position to an extended position.
According to yet other potentially preferred aspects of the invention, the face portion and body portion of the bolster of multipiece construction are formed from injection molded polymeric materials. The materials forming the face portion and the body portion are preferably of different durometers such that the face portion is more rigid than the body portion. The materials forming the face and the body portions may be either of similar or dissimilar chemical composition.
According to yet further potentially preferred aspects of the present invention, the face portion and body portion of the bolster of multipiece construction are joined along their peripheries by mateable projectile and aperture elements with intermediate ridges therebetween. The projectile and aperture elements are preferably fusion bonded to effect melt flow of the projectile elements within the aperture elements between the ridges.
In accordance with other potentially preferred aspects of the present invention the knee bolster includes mounting elements extending outwardly from the underside of the body portion facing away from the vehicle occupant for attachment to the vehicle frame. The mounting elements are preferably metal brackets which undergo flexure and subsequent plastic deformation upon impact by a vehicle occupant.
Advantageously, the knee bolster according to the present invention serves to provide a construction which is easily assembled and may be expanded to its operable position either with or without the use of an internally disposed air bag component. The orientation of expansion elements and the materials of construction may be selected to provide preferential expansion of designated regions of the bolster to enhance design alternatives.
Additional objects features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description. While the invention is illustrated and will be described in connection with potentially preferred embodiments, it is to be understood that such illustration and description are exemplary and explanatory only and are in no way to be construed as restrictive of the invention. On the contrary, it is the intent of the applicants to cover all alternatives, modifications, and equivalents as may be included within the true spirit and scope of the invention as limited only by the full scope of allowable claims.